The invention discloses a flare gas recovery process in the production process of polypropylene by an intermittent liquid-phase bulk method. The flare gas is collected in a vent line (200); polypropylene particles are removed by a dust collector (15); and then the flare gas is transported to a tail gas cabinet (14) for storage; after being compressed by a compressor (16) and condensed by a condenser (17), the tail gas enters a liquid storage tank (18); and non-condensable gas passes through a membrane separation system (13), the high-concentration propylene gas obtained by separation enters the tail gas cabinet (14); and extremely small amount of the lean propylene gas is discharged to a flare (20) by a flare gas vent buffer tank (19); thus actually reducing flare gas emission or even emitting no flare gas; when the content of the propylene at a primary membrane outlet is more than 30%, the flare gas enters a secondary membrane separation system, and a linkage program (100) is designed between a trip valve of a recovery buffer tank and the tail gas cabinet (14). The flare gas recovery process has the advantages of effectively recovering the propylene, environmental protection, saving resources and having positive popularization significance.